Charging refrigerating system



April 21, 1931.

R. w. DAVENPORT 1,801,625

CHARGING REFRIGERATING SYSTEMS Filed Feb. 4, 192a IVNVENTORT Pansofn W042 van 00ft By v I ATTORNEY.

Patented Apr. 21, 1931 UNITED STATES PATENT. OFFICE RANSOM W. DAVENPORT, 015 DETROIT, MICHIGAN, ASSIGNOR TO CHICAGO PNEUMATIC TOOL COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY CHARGING REFRIGERATING SYSTEM Application filed February 4, 1928. Serial No. 251,800.

This invention relates to refrigerating systems of the closed cycle type utilizing a lubricating working substance which is circulated through the system with alternate concen trating and diluting of the lubricant component in the low and high pressure parts of the system respectively. It has particular application to systems of the described type operating on the vapor-gas principle and using mutually soluble fluids for refrigeration and lubrication as disclosed and claimed in'my coplending application Ser. No. 151,671, filed ovember 30, 1926, although by no means confined thereto.

"Heretofore it has been proposed to mix the lubricating and volatile components of the working substance in definite proportions before adding the mixture or solution to the system but it has developed that such a method of charging frequently does not meet the whole range of operating conditions with equally satisfactory results. This is due to the fact that in a system such as disclosed in the above copending application the low pressure concentrator for the lubricant, as

. well as the compressor, may vary greatly in temperature not only during each cycle of operation but from day to day as the seasons change. Thus with a mixture of the correct Volume and proportions for satisfactory operation on a moderately warm day of 72 F. rise in room temperature to 90 with the consequent greater evaporation of the volatile ingredient of the Working substance may so overcharge the concentrator that the liquid passing to the pump may be so dilute or unconcentrated as to cause serious impairment of the volumetric efliciency of the pump. Under such circumstances the system will WOrk as if the proportions of the mixture were wrong and too much volatile liquid had been used.

One object of the invention is to devise improved methods of charging refrigerating systems which utilize working substances containing mutually soluble lubricating and refrigerating fluids. Another object is to provide a method for adjusting the pro ortions of lubricating and refrigerating uids to meet the varying conditions of operating service. Other objects will be evident from the detailed description which follows:

To assist in the disclosure of the invention the accompanying drawin contains a single view diagrammatically in 'cating the parts of a refrigerating system in their operative relation, the view conforming in general to that of Fig. 1 of my copending application, Serial No. 151,671, referred to above.

In the drawing the refrigerating apparatus is shown as comprising an evaporator A, a compressor or pumpJ B, a condenser C and an expansion device the parts being suitably connected to operate as a closed cycle system. The evaporator comprises a riser a and a downcomer a. The downcomer is provided for the purpose of securing concentration of the lubricant on the low pressure side of the system and to this end is provided with traps or pockets a forming a descending series toward compressor B. The operation conforms to that disclosed in my aforementioned copending application in which the working substance contained in riser a of the evaporator passes over intermittently in liquid form from riser a to downcomer a and is thereby washed in stages of progressively increased concentration of the lubricant component (while maintained under the suction pressure of compressor B) until it reaches compressor B as substantially pure lubricant.

For the volatile component of the working substance any known or suitable substance may be used, such as the low boiling liquids in common use-ammonia, sulphur dioxide, eth l chloride, etc. or preferably the higher boi ing substances comprising the ethyl and methyl chlorides, such as methylene chloride or carbon tetrachloride which are particularly adapted for use in closed cycle systems operating on the vapor-gas principle. The nonvolatile or lubricating component may be a lubricant in liquid or semi-liquid state having the requisite viscosity and soluble in the chosen volatile component.

Instead of attempting to fix the proportions and mix the ingredients before putting the same into the refrigerating system, the present invention contemplates a new charging process as follows: With apparatus of the type disclosed in the drawing, the first step consists in charging compressor B with a quantity of lubricant suflicient to operate it without overflow into the condenser C and evaporator A. The second step consists in charging the evaporator A with a quantity of volatlle liquid sufficient to cool something more than one-half its total length so that all movement of liquid stops off some distance short of compressor B. The third step consists in operating the system under service conditions in a room of the highest temperature which can reasonably be expected to occur (for example, 90 F.) for a sufiicient time to allow all temperatures in the system to become stable. The fourth step consists in adjusting the quantity of volatile liquid by addin to or withdrawing from the system, per erably at a point on the high side between pump band expansion device D, an amount just sufiicient to maintain the pipe connection from downcomer or concentrator a of the evaporator to pump B, slightly cool, while the system operates at the aforesaid maximum environing temperature.

The fourth step is most easily and quickly performed by adding a little too much of the volatile liquid during the second step. By adding too much volatile liquid the pipe connection from the concentrator a to compressor B will run cold. Then when the high side is vented during the fourth step the excess volatile liquid is withdrawn until the pipe connection to the pump warms up appreciably, thus showing that concentration is being completed in the downcom'er a and the concentrated lubricant is passing to the compressor at substantially the temperature of the refrigerating chamber.

When the charging process is carried out as set forth, the system operates with close approximation to the ideal. As the room cools down (or the environing temperature decreases), the proportion of volatile liquid in the pump increases thus compensating for the decreased evaporating effect in evaporator A. If under extremely cool conditions the quantity of liquid in compressor B becomes too great and overflows into condenser C and evaporator A, the increased proportion of non-volatile liquid in evaporator A does no harm, since the room or environin temperature is then so low that but little re rigeration is required.

The process herein disclosed is particularly useful in charging refrigerating systems operating on the vapor-gas principle and utilizing a volatile liquid having a relatively high boiling point as, for example, methylene chloride or carbon tetrachloride, since the high side of the system may be freely opened while the compressor is in op eration to adjust the proportions of the ingredient fluids and the quantity of liquid mixture in the system. Such volatile liquids permit the use of air as the inert and insoluble gas (which is requisite to the operation of the system on the vapor-gas principle), and the opening of the high side or in fact any portion of the system is possible at any time without varying the operating characteristics of the system so far as the use of the inert and insoluble gas component, per se, is involved.

While the invention has been herein dis closed in what is now considered to be its preferred form, it is to be understood that minor changes and variations may be made therein Without departing from the spirit and scope of the invention as set forth in the appended claims.

1 claim as my invention:

-l. The method of charging compresslon refrigerating systems using mutually soluble lubricating and refrigerating fluids which are alternately concentrated and diluted in the low and high pressure parts respectively, which comprises putting a quantity of each of the fluids in the system, subjecting the system to the maximum environing temperature, and so adjusting the respective quantities of said fluids that the said concentration under low pressure is approximately completed.

2. The method of charging compression refrigerating systems using mutually soluble lubricating and refrigerating fluids which are alternately concentrated and diluted in the low and high pressure parts respectively, which comprises putting a quantity of each of the fluids in the system, subjecting the system to the maximum environing temperature, and so adjusting the respective quantities of said fluids that the said concentration is approximately completed in the lower temperature part of said system.

3. The method of charging refrigerating systems of the evaporator-compressor-condenser type utilizing mutually soluble lubricating and refrigerating fluids which are alternately concentrated and diluted in the low and high pressure parts of the systems, respectively, which comprises putting a charge of lubricant fluid in the compressor and a charge of refrigerating fluid in the evaporator operating the system and subj ecting it to the desired maximum environing temperature, and adjusting the quantity of refrigerating fluid by adding the same to, or by withdrawing fluid from, the high pressure side of the system.

4. The method of charging refrigerating systems of the evaporator-compressor-condenser type having an evaporator of the riser and downcomer'type and utilizing mutually soluble lubricating and refrigerating fluids which are alternately concentrated and diluted in the high and low pressure parts of the system, respectively, which comprises putting a charge of lubricant fluid in the compressor and a charge of refrigerating" lit fluid in the evaporator, operating the system and subjecting it to the maximum environing temperature, and adjusting the quantity of refrigerating fluid in the system until the connection from the downcomer of the evaporator to the compressor is only slightly cool 5. The method of charging re igerating systems of the evaporator-compressor-condenser type having an evaporator of the riser and downcomer type and utilizing mutually soluble lubricating and refrigerating fluids which are alternately concentrated and diluted in the high and low pressure parts of the systems, respectively, which comprises putting a charge of lubricant fluid in the compressor and a slightly excessive charge of refrigerating fluid in the evaporator, operating the system and subjecting it to the desired maximum environing temperature, and withdrawing refrigerating fluid from, the high temperature side or the system until the connection from the downcomer of the evaporator to the compressor is only slightly cool.

6. The method of charging refrigerating systems of the evaporator-compressor-condenser type having an evaporator of the riser and downcomer type, the system operating on the vapor-gas principle and utilizing a harmless volatile liquid with a relatively high boiling point, a lubricant soluble in the volatile liquid, and an inert and insoluble gas, the lubricant being alternately concentrated and diluted in the low and high pressure parts of the system, respectively, which method comprises putting a charge of the volatile liquid in the evaporator and a charge of the lubricant in the compressor and a charge of the gas in the remainder of the system, operating the system and subjecting it to the desired maximum environing temperature, and adjusting the proportion of the liquid in the system by withdrawing fluid from the high pressure side of the system or adding volatile liquid thereto until the connection from the downcomer of the evaporator to the pump is only slightly cool,

Signed by me at Detroit, in the county of Wayne and State of Michigan, this 30th day of January, 1928,

RANSOM W. DAVENPORT. 

